List of primary NTHS expressways

The primary routes (主线) of National Trunk Highway System expressways of China are numbered with one- or two-digit designations. Generally, one-digit routes radiate from Beijing, for two-digit routes, odd-numbered routes under 90 run north–south, with lower numbers in the east and higher numbers in the west; even-numbered routes under 90 run east–west, with lower numbers in the north and higher numbers in the south; while 9X routes are zonal beltways.

Source: Wikipedia — List of primary NTHS expressways (CC BY-SA 4.0)